I received useful information in the comments to my blog.
“It seems to be easier to drink “Indigo naturalis” if you use an oblate when drinking it.” Indigo naturalis” is a very fine powder, difficult to swallow and has a unique taste, so if you don’t like it, try it.
[Comment excerpt.
The “Oblate” is a thin pouch, so by wrapping “Indigo naturalis” in it, it is possible to take it without the risk of choking or tasting the subtle taste of “Indigo naturalis. Indigo naturalis” is especially painful if choked. The oblongs are available for about 700 yen per 100 sheets, and I highly recommend them to those who have trouble swallowing “Indigo naturalis”. By the way, you can find them at regular drugstores for half the price and in half the quantity I mentioned earlier.
FYI.